Only allow single exit phi for reduction in try_create_reduction_list

2016-01-10  Tom de Vries  <tom@codesourcery.com>

	PR tree-optimization/69039
	* tree-parloops.c (try_create_reduction_list): Only allow single exit
	phi for reduction.

	* gcc.dg/autopar/pr69039.c: New test.

From-SVN: r232196

gcc/ChangeLog

+2016-01-10  Tom de Vries  <tom@codesourcery.com>
+
+	PR tree-optimization/69039
+	* tree-parloops.c (try_create_reduction_list): Only allow single exit
+	phi for reduction.
+
 2016-01-09  John David Anglin  <danglin@gcc.gnu.org>
 
 	PR middle-end/68743

gcc/testsuite/ChangeLog

+2016-01-10  Tom de Vries  <tom@codesourcery.com>
+
+	PR tree-optimization/69039
+	* gcc.dg/autopar/pr69039.c: New test.
+
 2016-01-09  Marek Polacek  <polacek@redhat.com>
 
 	PR c++/69113

gcc/testsuite/gcc.dg/autopar/pr69039.c

+/* { dg-do compile } */
+/* { dg-options "-O2 -ftree-parallelize-loops=2" } */
+
+unsigned int b;
+
+unsigned int
+fn1 (unsigned int d)
+{
+  int i;
+
+  for (i = 0; i < 1000; i++)
+    b |= d;
+
+  return b;
+}

gcc/tree-parloops.c

@@ -2595,6 +2595,14 @@ try_create_reduction_list (loop_p loop,
 			 "  FAILED: it is not a part of reduction.\n");
 	      return false;
 	    }
+	  if (red->keep_res != NULL)
+	    {
+	      if (dump_file && (dump_flags & TDF_DETAILS))
+		fprintf (dump_file,
+			 "  FAILED: reduction has multiple exit phis.\n");
+	      return false;
+	    }
+	  red->keep_res = phi;
 	  if (dump_file && (dump_flags & TDF_DETAILS))
 	    {
 	      fprintf (dump_file, "reduction phi is  ");